Method, Device, Computer Program Product and Data Processing Program For Handling Communication Link Problems Between A First Communication Means and A Second Communication Means

ABSTRACT

A method for handling communication link problems between a first communication means and a second communication means. Data signals, control signals and/or error information are transferred between the first communication means and the second communication means using the communication link. The method includes activating a static identification pattern in the first communication means representing an error information, and stopping a clock signal (Clk) inside the first communication means to freeze a present error condition, in response to a communication link problem being detected, and transferring the activated static identification pattern permanently and/or repeatedly to the second communication means using the communication link.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 from EuropeanPatent Application No. 09175676.7 filed Nov. 11, 2009, the entirecontents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of inter-chip communication.

2. Description of the Related Art

Current computing systems include a set of different chips, e.g.,microprocessors, I/O chips, memory chips, and have a system wide controlstructure for the major configuration, control and recovery functions.Such computer systems are either using dedicated interfaces between thedifferent chips for all communication that is related to these tasks oruse special command types that are traveling through the system usingthe main data path or interfaces.

For coupling of mainframes with high speed interfaces such asInfiniBand, special redundancy features for synchronizing system timesare needed. If a communication link between the coupling facility (CF),i.e. a communication means, and a system breaks, there can be severalreasons such as a broken or unplugged cable, or a communication meanswent into a check stop status because of an internal error, and/or anentire system went down and has stopped the communication means.

For coupling software or communication software it is important todistinguish between the different cases. In particular, it is importantto identify the case where the system stopped the communication meansbecause the whole system went down.

From the point of view of the communication means, whether the systemwent down or if the system stopped the chip for any other reason may notbe distinguishable. An exemplary implementation might be a mainframesystem in which a dedicated error line embedded in the maincommunication interface from the root complex to the communication meansis capable of stopping the communication means due to an internal erroror if the whole system went down. If the information that the systemerror line was active can be communicated to the other end of the link,the system software there can correlate events from different links anddraw the right conclusions for recovery of this situation.

With today's methodology, the error information can be transferred overthe communication link with manufacturer special flow control packets(SFCP) defined by OpCodes (Operation Codes), which are not used by thestandard interface protocol. These vendor specific packets can carrylittle payload for transferring data from one side to the other.

FIG. 1 shows a device for handling communication link problems between afirst communication means 10 and a second communication means 20, inaccordance with an embodiment of the prior art. The first communicationmeans 10 includes a first control means 12 connected to a firstinterface means 14, and the second communication means 20 includes asecond control means 22 connected to a second interface means 24. Thefirst communication means 10 and the second communication means 20 areeach part of a mainframe system 1, 2, wherein data signals and/orcontrol signals and/or error information are transferred between thefirst communication means 10 and the second communication means 20 usingthe communication link 5 build between the first interface means 14 andthe second interface means 24. In a memory means 16 the special flowcontrol packets (SFCP) defined by OpCodes (Operation Codes), which arenot used by the standard interface protocol, are stored. In normaloperation, the connected first control means 12 feeds the firstinterface means 14 with a continuous sequence of data to be transferred,which in case of. a high speed serial interface as it is used for theInfiniBand or PCI express protocols are so-called ordered sets. Theseordered sets are serialized and transferred over the communication link5. In case of a communication problem the first control means 12transfers corresponding special flow control packets (SFCP) from thememory means 16 to the first interface means 14 being used to send thecorresponding error information to the second communication means 20. Inthe second communication means 20 the second control means 22 reportsthe error information to the error structure of the system.

A drawback of this approach is the fact that the chip clock signals Clkcoupled to the first control means 12 can not be stopped immediatelywhen the communication problem is occurring but must run some timelonger until the special flow control packets (SFCP) are transferredfrom the first control means 12 to the first interface means 14 andfurther on over the communication link 5 to the second interface means22 of the second communication means 20. This delayed clock stop resultsin debug data of less quality as the debug data is from a much laterpoint in time than the point in time when the communication problemoccurred.

SUMMARY OF THE INVENTION

According to an aspect of the invention, a method for handlingcommunication link problems between a first communication means and asecond communication means, which are part of at least one mainframesystem is presented. The method includes activating a staticidentification pattern representing an error information in the firstcommunication means, stopping a clock signal (Clk) inside the firstcommunication means to freeze a present error condition in response to acommunication link problem being detected, and transferring theactivated static identification pattern permanently or repeatedly to thesecond communication means using the communication link. In addition, atleast one of a data signal, a control signal or error information istransferred between the first communication means and the secondcommunication means using the communication link.

In another aspect of the invention, a device for handling communicationlink problems between a first communication means and a secondcommunication means is presented. The first communication means includesa first control means connected to a first interface means. The secondcommunication means includes a second control means connected to asecond interface means. Data signals, control signals or errorinformation are transferred between the first communication means andthe second communication means using the communication link.

The device includes a generation means adapted to generate at least onestatic identification pattern, a switching means arranged between thefirst control means and the first interface means and responsive to atleast one activated error control signal (Err_ctrl_sign) or system errorline for switching a connection to the first interface means between thefirst control means and the generation means. Corresponding to the atleast one activated error control signal (Err_ctrl_sign) or system errorline, a clock signal (Clk) inside the first communication means isstopped to freeze a present error condition. The connection between thegeneration means and the interface means is set by the switching meansto send an activated static identification pattern permanently orrepeatedly to the second communication means using the communicationlink.

In yet another aspect of the present invention, a data processingprogram for execution in a data processing system including softwarecode portions for performing a method for handling communication linkproblems between a first communication means and a second communicationwhen the program is run on the data processing system is presented. Themethod includes activating a static identification pattern representingan error information in the first communication means, stopping a clocksignal (Clk) inside the first communication means to freeze a presenterror condition in response to a communication link problem beingdetected, and transferring the activated static identification patternpermanently or repeatedly to the second communication means using thecommunication link. At least one of a data signal, a control signal orerror information is transferred between the first communication meansand the second communication means using the communication link.

In still another aspect of the present invention, a computer programproduct stored on a computer-usable medium, including computer-readableprogram means for causing a computer to perform a method for handlingcommunication link problems between a first communication means and asecond communication means when the program is run on the computer isprovided. The method includes activating a static identification patternrepresenting an error information in the first communication means,stopping a clock signal (Clk) inside the first communication means tofreeze a present error condition in response to a communication linkproblem being detected; and transferring the activated staticidentification pattern permanently or repeatedly to the secondcommunication means using the communication link. At least one of a datasignal, a control signal or error information is transferred between thefirst communication means and the second communication means using thecommunication link.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention, as described in detail below,is shown in the drawings, in which

FIG. 1 is a schematic block diagram of a device for handlingcommunication link problems between a first communication means and asecond communication means, in accordance with an embodiment of therelated art;

FIG. 2 is a schematic block diagram of a device for handlingcommunication link problems between a first communication means and asecond communication means, in accordance with a first embodiment of thepresent invention;

FIG. 3 is a schematic block diagram of a device for handlingcommunication link problems between a first communication means and asecond communication means, in accordance with a second embodiment ofthe present invention; and

FIG. 4 is a schematic flow chart of a method for handling communicationlink problems between a first communication means and a secondcommunication means in accordance with an embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The technical problem underlying the invention is to provide a methodand a device for handling communication link problems between a firstcommunication means and a second communication means, which are able todetect and to distinguish between problems of a communication link andto perform a clock stop as soon as possible, and to provide a dataprocessing program and a computer program product to perform the methodfor handling communication link problems between a first communicationmeans and a second communication means.

According to the invention this problem is solved by providing a methodfor handling communication link problems between a first communicationmeans and a second communication means having the features of claim 1, adevice for handling communication link problems between a firstcommunication means and a second communication means having the featuresof claim 8, a data processing program for performing the method forhandling communication link problems between a first communication meansand a second communication means having the features of claim 14, and acomputer program product causing a computer to perform the method forhandling communication link problems between a first communication meansand a second communication means having the features of claim 15.Advantageous embodiments of the invention are mentioned in the subclaims.

Accordingly, in an embodiment of the present invention a method forhandling communication link problems between a first communication meansand a second communication means, especially being part of at least onemainframe system is presented. The data signals and/or control signalsand/or error information are transferred between the first communicationmeans and the second communication means using the communication link.The method may include activating a static identification pattern in thefirst communication means representing an error information, andstopping a clock signal inside the first communication means to freeze apresent error condition, in response to a communication link problembeing detected, and transferring the activated static identificationpattern permanently and/or repeatedly to the second communication meansusing the communication link.

In further embodiments of the present invention, a given number ofstatic identification patterns are used to represent differentcommunication link problems, wherein each static identification patternis assigned to one communication link problem.

In further embodiments of the present invention, the staticidentification pattern is activated in accordance to a correspondingerror control signal and/or system error line activated in response to acommunication link problem being detected.

In further embodiments of the present invention, different communicationlink problems are causing different error control signals and/or systemerror lines being activated.

In further embodiments of the present invention, a communication linkproblem is detected, when a disconnection of a cable occurs and/or anoperation of the first communication means is stopped due to an internalerror and/or the operation of the first communication means is stoppeddue to system break down.

In further embodiments of the present invention, the transferred staticidentification pattern is detected at the second communication means anda corresponding error condition is reported to a system error structure,wherein a broken communication link is detected at the secondcommunication means due to a fact that no data signals and/or controlsignals and no static identification pattern are received at the secondcommunication means.

In further embodiments of the present invention, the staticidentification patterns are symbols not part of an alphabet being usedduring regular communication over the communication link and/or aresymbols of the alphabet being used in a way, that at least one rule of acorresponding communication protocol is hurt.

In another embodiment of the present invention, a device for handlingcommunication link problems between a first communication means and asecond communication means, wherein the first communication meansincludes a first control means connected to a first interface means, andthe second communication means includes a second control means connectedto a second interface means is shown. Data signals and/or controlsignals and/or error information are transferred between the firstcommunication means and the second communication means using thecommunication link. Included are generation means adapted to generate atleast one static identification pattern, and a switching means arrangedbetween the first control means and the first interface means andresponsive to at least one activated error control signal and/or systemerror line for switching a connection to the first interface meansbetween the first control means and the generation means. Correspondingto at least one activated error control signal and/or system error linea clock signal inside the first communication means is stopped to freezea present error condition. The connection between the generation meansand the interface means is set by the switching means to send anactivated static identification pattern permanently and/or repeatedly tothe second communication means using the communication link.

In further embodiments of the present invention, the generation meansincludes at least one storage means, adapted to store at least onestatic identification pattern.

In further embodiments of the present invention, inside at least onestorage means at least one static identification pattern is implementedas hard-wired logic.

In further embodiments of the present invention, the generation meansand/or the switching means are activating at least one staticidentification pattern in response to at least one error control signaland/or system error line.

In further embodiments of the present invention, the transferred staticidentification pattern is received at the second communication means bythe second interface means and the second control means is reporting acorresponding error condition to a system error structure, wherein thesecond control means is reporting a broken communication link to thesystem error structure detected due to a fact that no data signalsand/or control signals and no static identification pattern are receivedat the second communication means.

In further embodiments of the present invention, the switching meansinclude a multiplexer.

In another embodiment of the present invention, a data processingprogram for execution in a data processing system includes software codeportions for performing a method for handling communication linkproblems between a first communication means and a second communicationmeans when the program is run on the data processing system.

In yet another embodiment of the present invention, a computer programproduct stored on a computer-usable medium, includes computer-readableprogram means for causing a computer to perform a method for handlingcommunication link problems between a first communication means and asecond communication means when the program is run on the computer.

All in all, embodiments of the invention disclosed herein are able todetect and to distinguish between problems of a communication link andto perform a clock stop immediately after the error control signaland/or the system error line is activated. So embodiments of theinvention allow the communication of the error information over thecommunication link together with an immediate clock stop. This earlyclock stop results in a very high quality of the debug data, since thereis less delay time between the point in time of the clock stop and thepoint in time were the error causing communication problems occurred.

The above, as well as additional purposes, features, and advantages ofthe present invention will become apparent in the following detailedwritten description.

In the drawings, equal or similar elements are referred to by equalreference numerals. The drawings are merely schematic representations,not intended to portray specific parameters of the invention. Moreover,the drawings are intended to depict only typical embodiments of theinvention and therefore should not be considered as limiting the scopeof the invention.

FIG. 2 shows a device for handling communication link problems between afirst communication means 110 and a second communication means 210, inaccordance with a first embodiment of the present invention.

Referring to FIG. 2, the shown embodiment of the invention employs adevice for handling communication link problems between a firstcommunication means 110 of a first mainframe system 101 and a secondcommunication means 210 of a second mainframe system 102. In the shownembodiment the first communication means 110 acts as sending means andthe second communication means 210 acts as receiving means. The firstcommunication means 110 includes a first control means 120 connected toa first interface means 140, and the second communication means 210includes a second control means 220 connected to a second interfacemeans 240, wherein data signals and/or control signals and/or errorinformation are transferred between the first communication means 110and the second communication means 210 using the communication link 105.

According to the invention the device for handling communication linkproblems includes a generation means 160 adapted to generate at leastone static identification pattern 162, 164, 166, and a switching means150 arranged between the first control means 120 and the first interfacemeans 140 and responsive to at least one activated error control signalErr_ctrl_sign and/or system error line for switching a connection to thefirst interface means 140 between the first control means 120 and thegeneration means 160. A multiplexer could be used as switching means 150to pass a dedicated static identification pattern 162, 164, 166 to thefirst interface means 140 which will then be transferred over thecommunication link 105 permanently and/or repeatedly for signalling aclock stop because of the active error control signal and/or error line.This special static identification pattern 162, 164, 166 can be detectedat the second communication means 210 and a corresponding errorinformation can be reported to a system error structure.

In normal operation, the switching means 150 is connecting the firstcontrol means 120 to the first interface means 140 and the connectedfirst control means 120 feeds the first interface means 140 with acontinuous sequence of data to be transferred, which in case of e.g. ahigh speed serial interface as it is used for the InfiniBand or PCIexpress protocols are so-called ordered sets. These ordered sets areserialized and transferred over the communication link 105.

In response to a communication link problem being detected at least oneerror control signal Err_ctrl_sign and/or system error line isactivated. In response to the activated at least one error controlsignal Err_ctrl_sign and/or system error line a clock signal Clk insidethe first communication means 110 coupled to the first control means 120is stopped to freeze a present error condition, and the connectionbetween the generation means 160 and the interface means 140 is set bythe switching means 150 to send an activated static identificationpattern 162, 164, 166 permanently and/or repeatedly to the secondcommunication means 210 using the communication link 105. The clocksignals Clk of the first and second interface means 140, 240 driving thewires between the first and second communication means 110, 210 need notto be stopped as no detailed debug information may be pulled out ofthem. When the clock signals Clk of the first control means 120 arestopped, no data like mentioned sequence of ordered sets will be passedto the first interface means 140 anymore but only one of the staticidentification patterns 162, 164, 166. Additional in the shownembodiment a storage means adapted to store at least one staticidentification pattern 162, 164, 166 is used as generation means 160which is activating the at least one static identification pattern 162,164, 166 in response to the at least one error control signalErr_ctrl_sign.

Still referring to FIG. 2 three static identification patterns 162, 164,166 are used to represent different communication link problems, whereineach static identification pattern 162, 164, 166 is assigned to onecommunication link problem, wherein one of the static identificationpattern 162, 164, 166 is activated in accordance to a correspondingerror control signal Err_ctrl_sign and/or system error line activated inresponse to a communication link problem being detected. The differentcommunication link problems are causing different error control signalsErr_ctrl_sign and/or system error lines being activated. A communicationlink problem is detected, for example, when a disconnection of a cableoccurs and/or an operation of the first communication means 110 isstopped due to an internal error and/or the operation of the firstcommunication means 110 is stopped due to system break down.

In the shown embodiment a first static identification pattern 162 isactivated in accordance to a first error control signal Err_ctrl_signand/or system error line which is activated if the operation of thefirst communication means 110 is stopped due to an internal error. Asecond static identification pattern 164 is activated in accordance to asecond error control signal Err_ctrl_sign and/or system error line whichis activated if the operation of the first communication means 110 isstopped due to system break down. A third static identification pattern166 is activated in accordance to a third error control signalErr_ctrl_sign and/or system error line which is activated ifdisconnection of a cable is detected. As constant identificationpatterns 162, 164, 166 symbols are selected, which are not part of theregular alphabet so that the second communication means 210 can surelyidentify this symbols as unique characteristics for the activated errorcontrol signal Err_ctrl_sign and/or system error line. Additionally oralternatively symbols of the alphabet may be used as constantidentification patterns in a way, that at least one rule of acorresponding communication protocol is hurt. Additionally a brokencommunication link 105 can be detected by the second control means 220at the second communication means 210 due to a fact that no data signalsand/or control signals and no static identification pattern 162, 164,166 are received at the second communication means 210. So the secondcontrol means 220 is reporting a broken communication link 105 to thesystem error structure detected due to the fact that no data signalsand/or control signals and no static identification pattern 162, 164,166 are received at the second communication means 210.

For the coupling and/or communication software it is important todistinguish between the different cases, in particular it is importantto identify the case where the mainframe system 101 stopped the firstcommunication means 110 while the whole system 101 went down. From thepoint of view of the first communication means 110, it might not bedistinguishable, whether the system went down or if the system 101stopped the chip 110 for any other reason. An exemplary implementationmight be a mainframe system 101 in which a dedicated error line embeddedin the main communication interface from the root complex to the firstcommunication means 120 is capable to stop the communication means 120due to an internal error or the whole system 101 went down. If theinformation that the system error line was active can be communicated tothe other end of the communication link 105 i.e. to the secondcommunication means 210 of the second main frame system 102, the systemsoftware there can correlate events from different links and draw theright conclusions for recovery of this situation. For example, in amaster-slave-system where the first main frame system 101 is acting asmaster system and the second main frame system 102 is acting as slave orback up system, it is very important for the second main frame system102 to know, that the first main frame system 101 went down, so thesecond main frame system 102 has to act as master system. Since everypossible communication problem is activating a corresponding staticidentification pattern 162, 164, 166 the second control means 220 of thesecond communication means 210 is also able to detect a brokencommunication link 105 due to the fact that during a communicationprocess no data signals and/or control signals and no staticidentification pattern 162, 164, 166 are received at the secondcommunication means 210. So the second main frame system 102 is going onacting as slave or back up system in case of a mechanical break of thecommunication link 105 since the first main frame system 102 is stillworking as master. Such a situation can occur, for example, when acommunication cable is mechanically disrupted.

FIG. 3 shows a device for handling communication link problems between afirst communication means 110′ and a second communication means 210, inaccordance with a second embodiment of the present invention.

Referring to FIG. 3, the shown embodiment of the invention employs adevice for handling communication link problems between a firstcommunication means 110′ of a first mainframe system 101′ and a secondcommunication means 210 of a second mainframe system 102. Like in theembodiment shown in FIG. 2 the first communication means 110′ acts alsoas sending means and the second communication means 210 acts asreceiving means. The first communication means 110′ includes a firstcontrol means 120 connected to a first interface means 140, and thesecond communication means 210 includes a second control means 220connected to a second interface means 240, wherein data signals and/orcontrol signals and/or error information are transferred between thefirst communication means 110 and the second communication means 210using the communication link 105.

According to the invention the device for handling communication linkproblems includes a generation means 160′ adapted to generate at leastone static identification pattern 162′, 164′, 166′, and a switchingmeans 150′ arranged between the first control means 120 and the firstinterface means 140 and responsive to at least one activated errorcontrol signal Err_ctrl_sign and/or system error line for switching aconnection to the first interface means 140 between the first controlmeans 120 and the generation means 160′. A multiplexer could be used asswitching means 150′ to pass a dedicated static identification pattern162′, 164′, 166′ to the first interface means 140 which will then betransferred over the communication link 105 permanently and/orrepeatedly for signalling a clock stop because of the active errorcontrol signal and/or error line. This special static identificationpattern 162′, 164′, 166′ can be detected at the second communicationmeans 210 and a corresponding error information can be reported to asystem error structure.

As in the first embodiment of FIG. 2, in the second embodiment of FIG. 3a storage means adapted to store at least one static identificationpattern 162′, 164′, 166′ is used as generation means 160′. But unlikethe first embodiment of FIG. 2 in the second embodiment of FIG. 3 atleast one static identification pattern 162′, 164′, 166′ is implementedinside the at least one storage means 160′ as hard-wired logic, whereinthe switching means 150′ is activating the at least one staticidentification pattern 162′, 164′, 166′ in response to the at least oneerror control signal Err_ctrl_sign and/or system error line.

In normal operation, the switching means 150′ is connecting the firstcontrol means 120 to the first interface means 140 and the connectedfirst control means 120 feeds the first interface means 140 with acontinuous sequence of data to be transferred, which in case of a highspeed serial interface as it is used for the InfiniBand or PCI expressprotocols are so-called ordered sets. These ordered sets are serializedand transferred over the communication link 105.

In response to a communication link problem being detected at least oneerror control signal Err_ctrl_sign and/or system error line isactivated. In response to the activated at least one error controlsignal Err_ctrl_sign and/or system error line a clock signal Clk insidethe first communication means 110′ coupled to the first control means120 is stopped to freeze a present error condition, and the connectionbetween one of the three hard-wired static identification patterns 162′,164′, 166′ of the generation means 160′ and the interface means 140 isset by the switching means 150′ to send an activated staticidentification pattern 162′, 164′, 166′ permanently and/or repeatedly tothe second communication means 210 using the communication link 105. Theclock signals Clk of the first and second interface means 140, 240driving the wires between the first and second communication means 110′,210 need not be stopped as no detailed debug information may be pulledout of them. When the clock signals Clk of the first control means 120′are stopped, no data like mentioned sequence of ordered sets will bepassed to the first interface means 140 anymore but only one of thestatic identification patterns 162′, 164′, 166′.

Like the first embodiment of FIG. 2 three static identification patterns162′, 164′, 166′ are used in the second embodiment of FIG. 3 torepresent different communication link problems. In the shown secondembodiment a first static identification pattern 162′ is activated inaccordance to a first error control signal Err_ctrl_sign and/or systemerror line which is activated if the operation of the firstcommunication means 110′ is stopped due to an internal error, wherein asecond static identification pattern 164′ is activated in accordance toa second error control signal Err_ctrl_sign and/or system error linewhich is activated if the operation of the first communication means110′ is stopped due to system break down. A third static identificationpattern 166′ is activated in accordance to a third error control signalErr_ctrl_sign and/or system error line which is activated ifdisconnection of a cable is detected. As constant identificationpatterns 162′, 164′, 166′ also symbols are selected, which are not partof the regular alphabet so that the second communication means 210 cansurely identify this symbols as unique characteristics for the activatederror control signal Err_ctrl_sign and/or system error line. Like thefirst embodiment of FIG. 2 additionally or alternatively symbols of thealphabet may be used as constant identification patterns in a way, thatat least one rule of a corresponding communication protocol is hurt.Additionally a broken communication link 105 can be detected by thesecond control means 220 at the second communication means 210 due to afact, that during a communication process no data signals and/or controlsignals and no static identification pattern 162′, 164′, 166′ arereceived at the second communication means 210. So in this case thesecond control means 220 is reporting a broken communication link 105 tothe system error structure detected.

In the shown embodiments of FIGS. 2 and 3 three static identificationpatterns 162, 164, 166 or 162′, 164′, 166′ are used, but the scope ofthe invention is not limited to three static identification patterns soany different number less or more than three static identificationpatterns can be used to report different error information according tothe invention.

FIG. 4 shows a method for handling communication link problems between afirst communication means 110, 110′ and a second communication means 210in accordance with an embodiment of the present invention.

Referring to FIG. 4 the flowchart depicts how the devices for handlingcommunication link problems will be used. After an initialization acommunication link 105 between a sending means 110, 110′ and a receivingmeans 210 is build up in step S10. In step S20 the error control signalErr_ctrl_sign and/or system error line is activated if a communicationlink problem has been detected. In step S30 one of the staticidentification patterns 162, 164, 166 or 162′, 164′, 166′ is activatedin the sending means 110, 110′ corresponding to the activated errorcontrol signal Err_ctrl_sign and/or system error line. In step S40 theclock signal Clk coupled to the first control means 120 inside thesending means 110, 110′ is stopped to freeze the present errorcondition.

Alternatively Step S30 and S40 can be performed simultaneously or theorder of Step S30 and S40 can be changed. In step S50 the activatedstatic identification pattern 162, 164, 166, 162′, 164′, 166′ ispermanently and/or repeatedly transferred to the receiving means 210. Instep S60 the transferred static identification pattern 162, 164, 166,162′, 164′, 166′ is detected at the receiving means 210. In step S70 theerror information corresponding to the detected static identificationpattern is reported to a system error structure.

The inventive method for handling communication link problems between afirst communication means and a second communication means can beimplemented as an entirely software embodiment, or an embodimentcontaining both hardware and software elements. In a preferredembodiment, the invention is implemented in software, which includes butis not limited to firmware, resident software, microcode, etc.

Furthermore, the invention can take the form of a computer programproduct accessible from a computer-usable or computer-readable mediumproviding program code for use by or in connection with a computer orany instruction execution system. For the purposes of this description,a computer-usable or computer-readable medium can be any apparatus thatcan contain, store, communicate, propagate, or transport the program foruse by or in connection with the instruction execution system,apparatus, or device.

The medium can be an electronic, magnetic, optical, electromagnetic,infrared, or semiconductor system (or apparatus or device) or apropagation medium. Examples of a computer-readable medium include asemiconductor or solid state memory, magnetic tape, a removable computerdiskette, a random access memory (RAM), a read-only memory (ROM), arigid magnetic disk, and an optical disk. Current examples of opticaldisks include compact disk-read only memory (CD-ROM), compactdisk-read/write (CD-R/W), and DVD.

A data processing system suitable for storing and/or executing programcode will include at least one processor coupled directly or indirectlyto memory elements through a system bus. The memory elements can includelocal memory employed during actual execution of the program code, bulkstorage, and cache memories which provide temporary storage of at leastsome program code in order to reduce the number of times code must beretrieved from bulk storage during execution. Input/output or I/Odevices (including but not limited to keyboards, displays, pointingdevices, etc.) can be coupled to the system either directly or throughintervening I/O controllers.

Network adapters may also be coupled to the system to enable the dataprocessing system to become coupled to other data processing systems orremote printers or storage devices through intervening private or publicnetworks. Modems, cable modems, and Ethernet cards are just a few of thecurrently available types of network adapters.

Therefore embodiments of the invention include a device and a method forhandling communication link problems between a first communication meansand a second communication means which are able to detect and todistinguish between problems of a communication link and to perform aclock stop as soon as possible. This early clock stop results in a veryhigh quality of the debug data, since there is less delay time betweenthe point in time of the clock stop and the point in time were the errorcausing communication problems occurred.

1. A method for handling communication link problems between a firstcommunication means and a second communication means which are part ofat least one mainframe system, the method comprising: activating astatic identification pattern representing an error information in thefirst communication means; stopping a clock signal (Clk) inside thefirst communication means to freeze a present error condition inresponse to a communication link problem being detected; transferringthe activated static identification pattern permanently or repeatedly tothe second communication means using a communication link; wherein atleast one of a data signal, a control signal and error information istransferred between the first communication means and the secondcommunication means using the communication link.
 2. The methodaccording to claim 1, wherein a given number of static identificationpatterns are used to represent different communication link problems,and each static identification pattern is assigned to a communicationlink problem.
 3. The method according to claim 1, wherein the staticidentification pattern is activated in accordance to at least one of acorresponding error control signal (Err_ctrl_sign) and a system errorline activated in response to a communication link problem beingdetected.
 4. The method according to claim 3, wherein differentcommunication link problems are causing at least one of a differenterror control signal (Err_ctrl_sign) and system error line to beactivated.
 5. The method according to claim 1, wherein a communicationlink problem is detected when: a disconnection of a cable occurs, anoperation of the first communication means is stopped due to an internalerror, or the operation of the first communication means is stopped dueto system break down.
 6. The method according to claim 1, wherein thetransferred static identification pattern is detected at the secondcommunication means and a corresponding error condition is reported to asystem error structure, and a broken communication link is detected atthe second communication means due to a fact that during a communicationprocess no data signals or control signals and no static identificationpattern are received at the second communication means.
 7. The methodaccording to claim 1, wherein the static identification patterns aresymbols not part of an alphabet being used during regular communicationover the communication link or are symbols of the alphabet being used ina way that at least one rule of a corresponding communication protocolis hurt.
 8. A device for handling communication link problems between afirst communication means and a second communication means, especiallyfor performing the method according to claim 1, wherein the firstcommunication means comprises a first control means connected to a firstinterface means, and the second communication means comprises a secondcontrol means connected to a second interface means, wherein datasignals, control signals or error information are transferred betweenthe first communication means and the second communication means usingthe communication link, the device comprising: a generation meansadapted to generate at least one static identification pattern; aswitching means arranged between the first control means and the firstinterface means and responsive to at least one activated error controlsignal (Err_ctrl_sign) or system error line for switching a connectionto the first interface means between the first control means and thegeneration means; wherein corresponding to the at least one activatederror control signal (Err_ctrl_sign) or system error line a clock signal(Clk) inside the first communication means is stopped to freeze apresent error condition, and the connection between the generation meansand the interface means is set by the switching means to send anactivated static identification pattern permanently or repeatedly to thesecond communication means using the communication link.
 9. The deviceaccording to claim 8, wherein the generation means comprise at least onestorage means adapted to store at least one static identificationpattern.
 10. The device according to claim 9, wherein inside the atleast one storage means the at least one static identification patternis implemented as hard-wired logic.
 11. The device according to claim 8,wherein the generation means or the switching means is activating atleast one static identification pattern in response to the at least oneerror control signal (Err_ctrl_sign) or system error line.
 12. Thedevice according to claim 8, wherein the transferred staticidentification pattern is received at the second communication means bythe second interface means and the second control means is reporting acorresponding error information to a system error structure, wherein thesecond control means is reporting a broken communication link to thesystem error structure detected due to a fact that during acommunication process no data signals or control signals and no staticidentification pattern are received at the second communication means.13. The device according to claim 8, wherein the switching meanscomprise a multiplexer.
 14. A data processing program for execution in adata processing system comprising software code portions for performinga method for handling communication link problems between a firstcommunication means and a second communication when the program is runon the data processing system, the method comprising: activating astatic identification pattern representing an error information in thefirst communication means; stopping a clock signal (Clk) inside thefirst communication means to freeze a present error condition inresponse to a communication link problem being detected; andtransferring the activated static identification pattern permanently orrepeatedly to the second communication means using the communicationlink; wherein at least one of a data signal, a control signal or errorinformation is transferred between the first communication means and thesecond communication means using the communication link.
 15. A computerprogram product stored on a computer-usable medium, comprisingcomputer-readable program means for causing a computer to perform amethod for handling communication link problems between a firstcommunication means and a second communication means when the program isrun on the computer, the method comprising: activating a staticidentification pattern representing an error information in the firstcommunication means; stopping a clock signal (Clk) inside the firstcommunication means to freeze a present error condition in response to acommunication link problem being detected; and transferring theactivated static identification pattern permanently or repeatedly to thesecond communication means using the communication link; wherein atleast one of a data signal, a control signal or error information istransferred between the first communication means and the secondcommunication means using the communication link.